add loan and loan_charges model

app/models/transactions.py

@@ -20,6 +20,19 @@ class Transaction(db.Model):
     def __repr__(self):
         return f'<Transaction {self.id}>'
 
+    def to_dict(self):
+        """
+        Convert the Transaction object to a dictionary format for JSON serialization.
+        """
+        return {
+            'id': self.id,
+            'transaction_id': self.transaction_id,
+            'account_id': self.account_id,
+            'customer_id': self.customer_id,
+            'type': self.type,
+            'channel': self.channel,
+        }
+
     @classmethod
     def get_transaction_by_transaction_id(cls, transaction_id):
         return cls.query.filter_by(transaction_id=transaction_id).first()